refactor: consolidate icons and move server edit to separate page

- Create centralized icons file at src/components/icons/index.tsx
- Update admin and AppShell icons to re-export from centralized location
- Replace trial "T" button with GiftIcon in AdminServers
- Move server editing from modal to dedicated page /admin/servers/:id/edit
- Add localization keys for server edit page (mainSettings, pricingAndLimits, updateError)

src/locales/zh.json

@@ -1174,7 +1174,10 @@
       "enable": "启用",
       "disable": "禁用",
       "toggleTrial": "切换试用",
-      "loadError": "加载服务器失败"
+      "loadError": "加载服务器失败",
+      "mainSettings": "基本设置",
+      "pricingAndLimits": "价格和限制",
+      "updateError": "保存更改失败"
     },
     "campaigns": {
       "title": "广告活动",